Structural analysis

Goal

The aim is to perform structural (morphology, crystal structure, defects,…) and chemical analyses of nanostructures (thin films, 2 dimensional heterostructures, quantum dots (QDs), nanowires) obtained by Molecular Beam Epitaxy (MBE) or Metal Organic Vapor Deposition (MOCVD) to improve the understanding of the growth mechanisms as well as their optical and electro-optical properties.

Experimental facilities

1) X-ray diffraction

Synchrotron facility

The laboratory develops several X-ray techniques dedicated to the study of nanomaterials at the ESRF (European Synchrotron Research Facility) in particular in the two French CRG beamlines BM32 and BM02. The aim is to reveal the structure of semiconductor heterostructures for example multiple quantum wells, quantum dots and wires. Some materials have been studied in details, very recently GaN/InGaN, GaN/AlGAN, InAs/GaAs and InAs/InP wires with longitudinal or transversal heterostructures. Playing with the versatility of synchrotron radiation in terms of wavelength and beam size and using state of the art setups (goniometers and controlled environments) several topics are presently under study. Most of these works try to resolve the strain and composition field in complex structures and their respective couplings. For this purpose, we use regularly :
- Grazing Incidence X-ray Diffraction (GIXRD) mappings to enhance the sensitivity to the surface.
- Anomalous measurements (i.e. change of energy) to have a chemical signature in the diffraction that can be unified with absorption effects with the Diffraction Anomalous Fine Structure (DAFS) method.
- Coherence Diffraction Imaging (CDI) to analyze strain fields in nanostructures with focused beams.
- Grazing Incidence Small Angle X-ray Scattering (GISAXS) to analyze the shape and distributions of the object assembly.
- Micro-Laue to map the strain under polychromatic illumination.
- Micro or nanobeams in diffraction or fluorescence. Moreover, some of these experiments are performed under specific environments. For example, in situ growths have been performed under the beam in an ultra-high vacuum chamber to study the formation of nitride quantum dots and wires.

Contacts : Joël Eymery
Collaboration : V. Favre-Nicolin (CEA et UGA), F. Rieutord (CEA), H. Renevier (LMGP-INPG).

2) Electron microscopy

Transmission Electron Microscopy (TEM)

Microstructural analyses are performed using the CEA-Plate-Forme de Nano-Caractérisation (PFNC) equipments for sample preparation (polishing, ion milling, Focussed Ion Beam (FIB),…) and TEM investigations (Jeol 4000EX 400kV, Jeol 3010 300kV, Probe corrected-FEI Titan 80-300kV, Probe and Image corrected FEI Titan Pico 80-300kV with monochromator).

The technics used involve conventional TEM imaging, High Resolution TEM (HR-TEM), High Resolution Scanning TEM (HR-STEM) with High Angle Annular Dark Field (HAADF) and Annular Bright Field (ABF) detectors, Energy Filtered Imaging (EFTEM) as well as EDX (Energy Dispersive x-ray) and EELS (Electron Energy Loss) spectroscopy. General information on TEM can be found for example here

Our main studies concern :
- Analyses of defects in heterostructures (dislocations, stacking faults,…)
- Strain mapping from HR-TEM or HR-STEM images using Geometrical Phase Analysis (GPA) and understanding of the strain relaxation mechanisms (elastic or plastic)
- Chemical composition determination at the local scale in case of interfaces, clusters, quantum dots,..

HR-TEM image of a GaN QD in AlN matrix showing the presence of Stacking Faults (SF) and dislocations The sample has been prepared in cross-section by mechanical polishing and ion milling
TEM structural analysis of a single ZnSe/CdS NW-QD. (a) Series of HRTEM images along an entire tilted NW attached to the substrate. The CdSe QD is located about 70 nm from the gold particle, in the boxed region. (b) HRTEM of the boxed region in a ; the dashed rectangle in b, c and d corresponds to the CdSe slice. (c) Geometrical phase analysis of the growth planes along the growth direction. (d) Line profiles made in c along the solid boxed region. The (0002) interplanar spacing for ZnSe is indicated by the horizontal dashed line.
Scheme of a GaN Nanowire(NW) with radial InGaN quantum wells. HAADF-STEM images of longitudinal and transverse sections of the NW (preparation by FIB). HR-TEM image showing the presence of stackiçng faults (SF)

Contacts : Catherine Bougerol
Collaboration : Martien den Hertog (Insitut Néel, SPMCE team)

Scanning Electron Microscopy (SEM) with EDX analysis

This is routinely used to characterize the morphology and the chemical composition of the samples after synthesis

Three equipments are available :
- Zeiss SEM with Brücker EDX detector and Hitachi D5500 SEM with EDX at the CEA-PFNC. These two instruments allow imaging in STEM mode
- Zeiss Ultra + SEM at Institut Néel

SEM image (DF-STEM mode ; Hitachi D5500) of a GaN nanowire with InGaN insertions. In (green) and Ga (red) content along the line crossing the insertions from EDX analysis
Cohérence quantique - CQ

Cohérence quantique - CQ

Révéler des phénomènes quantiques dans des circuits électroniques nanométriques
Hélium : du fondamental aux applications - HELFA

Hélium : du fondamental aux applications - HELFA

Hélium comme système modèle, hydrodynamique et turbulence, spatial et astrophysique, instrumentation et développement cryogénique.
Magnétisme et Supraconductivité - MagSup

Magnétisme et Supraconductivité - MagSup

Equipe Magnétisme et supraconductivité à l’Institut NEEL - Systèmes impliquant différents degrés de liberté comme la charge, le spin ou le réseau.
Optique et Matériaux - OPTIMA

Optique et Matériaux - OPTIMA

Rassembler une chaine de compétence complète qui va de la synthèse et l’élaboration de matériaux nouveaux à l’étude des propriétés optiques non linéaires et plasmoniques
Matériaux, Rayonnements, Structure - MRS

Matériaux, Rayonnements, Structure - MRS

Compréhension des propriétés physico-chimiques de matériaux complexes sur la base d’une connaissance fine de leur structure
Micro et NanoMagnétisme - MNM

Micro et NanoMagnétisme - MNM

Complementary expertise in fabrication, characterisation, and simulations for studies in nanomagnetism with applications in spin electronics and micro-systems
Nano-Electronique Quantique et Spectroscopie - QNES

Nano-Electronique Quantique et Spectroscopie - QNES

Transport électronique et spectroscopie locale de structures quantiques
Nano-Optique et Forces - NOF

Nano-Optique et Forces - NOF

Nano - optique et forces
Nanophysique et Semiconducteurs - NPSC

Nanophysique et Semiconducteurs - NPSC

Élaboration de nanostructures de semi-conducteurs III-V et II-VI et étude de leurs propriétés physiques en vue de nouvelles fonctionnalités
Nanospintronique et Transport Moléculaire - NanoSpin

Nanospintronique et Transport Moléculaire - NanoSpin

Studying magnetism at the nanoscale, where classical and quantum properties can be combined and used for molecular quantum spintronics
Semi-conducteurs à large bande interdite - SC2G

Semi-conducteurs à large bande interdite - SC2G

De la physique du diamant et autres semi-conducteurs à grand gap vers les applications en électronique et biotechnologies
Surfaces, Interfaces et Nanostructures - SIN

Surfaces, Interfaces et Nanostructures - SIN

Etudes expérimentales et théoriques de systèmes de basse dimensionnalité
Systèmes Hybrides de basse dimensionnalité - HYBRID

Systèmes Hybrides de basse dimensionnalité - HYBRID

Propriétés électroniques, optiques, vibrationnelles, mécaniques, et leur couplage à l’échelle quantique, de nouveaux systèmes hybrides (nanotubes, graphène, matériaux bi-dimensionnels, fonctionnalisés) que l’équipe développe.
Théorie de la Matière Condensée -TMC

Théorie de la Matière Condensée -TMC

Phénomènes physiques nouveaux dans les matériaux et systèmes modèles.
Thermodynamique et biophysique des petits systèmes - TPS

Thermodynamique et biophysique des petits systèmes - TPS

Instrumentation ultrasensible pour sonder les propriétés électronique et thermique : de la matière condensée à basse température aux systèmes biologiques à l’ambiante.
Théorie Quantique des Circuits - ThQC

Théorie Quantique des Circuits - ThQC

Étude théorique du transport électronique dans des dispositifs nanométriques aux propriétés quantiques remarquables.
Ultra-basses températures - UBT

Ultra-basses températures - UBT

La physique quantique à la limite des ultra-basses températures.

TEM studies of nanostructures

People Catherine Bougerol, R. André, H. Boukari, B. Daudin, H. Mariette, S. Tatarenko, T. Aichele, B. Amstatt, S. Founta, L. Maingault, R. Najjar, I.C. Robin Overview and results The goal of our electron microscopy work has been to obtain structural informations at the atomic scale on... > suite

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